Weldless boss for attaching lips to a work implement

ABSTRACT

A lug member includes a slide platform defining a slide groove that further defines a sliding direction, a first end that is disposed along the sliding direction, and a second end that is disposed along the sliding direction. A spacer engaging projection extends downwardly from the slide platform.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of application Ser. No.16/857,511, filed on Apr. 24, 2020, having the same title, claimingpriority thereto and incorporating its contents herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates to wear member retention to a workimplement such as a bucket, and the like. Specifically, the presentdisclosure relates to a hammerless and weldless boss for attaching wearmembers to such a work implement.

BACKGROUND

Earth-working and excavating machines, such as wheel loaders, cableshovels, drag lines, electric rope shovels (ERS), excavators, and frontshovels, include implements generally used for digging into, ripping, orotherwise moving earth, rocks, debris, or other materials. Suchimplements commonly are various types of buckets having shapes anddimensions dependent on the type of bucket and size of the machineemploying a particular bucket. These implements are subjected toabrasion and impacts that cause them to wear. To prolong the useful lifeof these implements, various shrouds, or wear members, can be connectedto the earth-working and excavating implements at areas which aresubject to wear. These wear members may be connected to the implementsusing a retention or attachment system that permits replacement of thewear members when they become worn to the extent that they should bereplaced.

Some implements which have been provided with wear members have requiredthat one or more components be welded to the implement in order topermit retention of the wear member in place on the implement. Otherimplements have employed various multi-component retaining systemswherein one or more of the components must be hammered in place to holda wear member in position on an implement. The use of welded componentsthat may need frequent replacement themselves due to extreme conditionsof wear may be problematic, particularly where maintenance must be doneat a work site. The use of retaining systems that are required to behammered in place also may be problematic and difficult to put in placeand remove. A shroud/wear member retention system that is both weldlessand hammerless, that is to say, one that does not require retentionparts to be welded to the implement and does not require retention partsthat must be hammered in place, would be both beneficial and desirable.In addition, an assembled shroud/wear member retention system shouldhave cooperating components that are arranged in a manner to avoidpremature failure.

For example, U.S. Pat. No. 10,407,880 discloses a retention system thatincludes a lug member and a boss member that is retained in a slidingmanner onto the lug member. The lug member may be inserted into anaperture found on the bucket or other work implement while the bossmember may be used with a retaining system commercially available underthe tradename of CAPSURE that allows a wear member to be attached to thebucket by simply rotating a lock retainer. If the wear member becomesworn, rotating the lock retainer into an unlocked configuration allowsthe wear member to be removed. If the boss member or other portion ofthe retention system needs to be replaced, then this can also beaccomplished easily.

However, this retention system does not work with all the workimplements and the wear members currently in the field due to variousdimensional differences of the disclosed retention system and theapertures of the work implement that receive the retention system.

SUMMARY

An attachment assembly for attaching a wear member to a work implementis provided according to an embodiment of the present disclosure. Theattachment assembly may comprise a spacer, and a lug member including aslide platform defining a slide groove that further defines a slidingdirection, a first end that is disposed along the sliding direction, anda second end that is disposed along the sliding direction. A spacerengaging projection may be provided on the lug member that defines aspacer engaging surface disposed proximate to the first end of the slideplatform along the sliding direction.

A lug member for use with attachment system for attaching wear membersto a work implement using a spacer is provided according to anembodiment of the present disclosure. The lug member may comprise aslide platform defining a slide groove that further defines a slidingdirection, a first end that is disposed along the sliding direction, anda second end that is disposed along the sliding direction. The lugmember may further comprise a spacer engaging projection that extendsdownwardly from the slide platform.

An attachment system for attaching a wear member to a work implement isprovided according to an embodiment of the present disclosure. Theattachment system may comprise a spacer, and a lug member including aslide platform defining a slide groove that further defines a slidingdirection, a first end that is disposed along the sliding direction, anda second end that is disposed along the sliding direction. A spacerengaging projection may be provided defining at least a first spacerengaging surface disposed proximate to the first end of the slideplatform along the sliding direction. A sliding boss member may also beprovided. The spacer may engage the at least first spacer engagingsurface, and the sliding boss member may be disposed in the slidegroove.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of thedisclosure and together with the description, serve to explain theprinciples of the disclosure. In the drawings:

FIG. 1 is a perspective view of a work implement such as a bucket orscoop that may use an attachment system for attaching a wear member suchas a shroud/wear member to the work implement according to variousembodiments of the present disclosure.

FIG. 2 is an enlarged perspective view of the bucket of FIG. 1 with thework tools and the shrouds/wear members removed, revealing an attachmentsystem according to an embodiment of the present disclosure shown in itsinstalled state.

FIG. 3 is a side sectional view of the bucket of FIG. 2 showing theattachment system retaining a wear member onto the lip of the bucket.

FIG. 4 is a partial exploded assembly view of a portion of theattachment system with the sliding boss member attached to the lugmember, forming a subassembly with the lug of the lug member beinginserted into the aperture of the bucket until the insertion is completeas illustrated in FIG. 5.

FIG. 5 illustrates the attachment system of FIG. 4 sliding rearwarduntil the lug catches the underside of the bucket as shown in FIG. 6,forming an undercut helping to prevent its removal along the directionof insertion as illustrated in FIG. 4.

FIG. 6 illustrates the rearward sliding of the sliding boss member untilthe sliding boss member achieves the rearmost position of FIG. 7.

FIG. 7 illustrates the insertion of a spacer used with the attachmentsystem of FIGS. 2 thru 6 into the aperture of the work implement. Thespacer is inserted until it engages the both the lug member and the wearmember as illustrated in FIG. 8.

FIG. 8 shows the spacer preventing forward movement of the lug member,helping to retain the attachment system in the aperture of the bucket.The sliding boss member is shown sliding forward until it passes overthe spacer as shown in FIG. 9.

FIG. 9 illustrates the attachment system locked into place, ready toreceive a wear member that is held onto the attachment system using theCAPSURE retaining system sold by the Assignee of the present application(see FIG. 3).

FIG. 10 is an exploded assembly view of an attachment system similar tothat shown in FIGS. 2 thru 9 without a spacer.

FIG. 11 shows the sliding functionality of the attachment system of FIG.10 (it is to be understood that a similar or identical slidingfunctionality and/or assembly is provided in the attachment system ofFIGS. 2 thru 9).

FIG. 12 shows the use of jam nuts to prevent unwanted movement of thesliding boss member once properly positioned.

FIG. 13 is a top view of the attachment system of FIG. 2 removed fromthe bucket, revealing its components more clearly including the spacer,the lug member, the sliding boss member, pin, and compression boltassemblies, etc.

FIG. 14 is a side view of the attachment system of FIG. 13.

FIG. 15 is a front view of the attachment system of FIG. 13.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the disclosure,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts. In some cases, a referencenumber will be indicated in this specification and the drawings willshow the reference number followed by a letter for example, 100 a, 100 bor by a prime for example, 100′, 100″ etc. It is to be understood thatthe use of letters or primes immediately after a reference numberindicates that these features are similarly shaped and have similarfunction as is often the case when geometry is mirrored about a plane ofsymmetry. For ease of explanation in this specification, letters andprimes will often not be included herein but may be shown in thedrawings to indicate duplications of features, having similar oridentical function or geometry, discussed within this writtenspecification.

Various embodiments of an apparatus and a method will be describedherein regarding an attachment system (may also be referred to as aretention system), a lug member, and a spacer for attaching a wearmember to a work implement such as a bucket assembly or the like.

In some embodiments, the attachment system may allow for easierreplacement of wear members for work implements already in the field.

FIG. 1 illustrates an implement 10 in the form of a bucket 12. Bucket 12may include one or more wear members 14 and wear member attachmentsystems 100 in accordance with disclosed embodiments. While implement 10is illustrated in FIG. 1 and described as a bucket 12, it should beunderstood that the disclosed embodiments of a wear member retentionsystem may be employed in connection with implements other than abucket.

For example, wear member attachment systems 100 according to disclosedembodiments may be employed on a separate ground engaging edge or lipmember that may then be attached to a bucket, scoop or other excavatingor material handling implement. Bucket 12 may be of the type employed invarious machines such as, for example, an electric rope shovel (shown inFIG. 1), a dragline, a hydraulic excavator, a backhoe, a tracked orwheeled loader, etc., and may be shaped somewhat differently dependingon the type of machine in which it is employed. Some buckets or otherimplements may include one or more apertures that may receive variousfasteners or retaining members intended to secure replaceable wearmembers of various types thereto. Such existing apertures mayconveniently be used in connection with disclosed embodiments of a wearmember attachment system 100.

Bucket 12 may include a lip portion 16, sometimes referred to as adigging edge, cutting edge, edge member, etc., and one or more wallmembers defining a container portion 17 for material. For example,container portion 17 of bucket 12 may include a primary wall member 18which may serve as a bottom and back, and two side wall members 20 and22. Other bucket forms are contemplated, depending on the type ofmachine on which the bucket may be employed. Lip portion 16 may beprovided with a plurality of tooth assemblies 24, and with a pluralityof wear members 14. For example, a wear member 14 may be providedbetween each pair of adjacent tooth assemblies 24. Lip portion 16 may bedetachable from bucket 12, e.g., secured by bolts or other fasteners, orit may be a fixed component of bucket 12, e.g., welded to primary wallmember 18, etc.

FIGS. 2 and 3 show the attachment system 100 in a fully installed state,ready to receive a wear member 14 that may be attached to the exposedboss 102 of the attachment system 100 using a retaining mechanism 50sold under the tradename of CAPSURE by the assignee of the presentdisclosure. The boss 102 may have any suitable shape such asfrustoconical, cylindrical, spherical, etc.

As best seen in FIG. 2, the attachment system 100 may be used forattaching a wear member 14 to a work implement 10 (e.g. bucket 12), andmay comprise a spacer 104, and a lug member 106 that includes a slideplatform 108 defining a slide groove 110 (see also FIG. 1) that furtherdefines a sliding direction 112 for the sliding boss member 114. Theslide platform 108 may also include a first end 116 (may also bereferred to as the front end) that is disposed along the slidingdirection 112, and a second end 118 (may also be referred to as the rearend, see FIG. 3) that is disposed along the sliding direction 112.

The lug member 106 may also include a spacer engaging projection 120defining at least a first spacer engaging surface 122 that is disposedproximate to the first end 116 of the slide platform 108 along thesliding direction 112 (i.e. is slightly forward of the first end 116 oreven therewith along the sliding direction 112). The at least firstspacer engaging surface 122 may engage the spacer 104. Also, the slidingboss member 114 may be disposed in the slide groove 110, and may be atleast partially disposed above the spacer 104, keeping the spacer 104from being move upwardly a great extent (see FIG. 3). This may not bethe case for other embodiments of the present disclosure

In some embodiments, the at least first spacer engaging surface 122 is afront facing surface 122 a (may be an arcuate surface but notnecessarily so). A second spacer engaging surface 124 may also beprovided that is facing upwardly (may be a horizontal flat surface butnot necessarily so).

As alluded to earlier herein, the work implement 10 defines an aperture26, and the spacer 104 as well as the spacer engaging projection 120 ofthe lug member 106 may be disposed in the aperture 26 with the spacer104 engaging the work implement 10, and the spacer engaging projection120 of the lug member 106 at the same time. Hence, the attachment systemis now fixed to the implement and will not unintentionally fall out ofthe aperture. The second spacer engaging surface 124 may help to preventthe spacer 104 from passing through the aperture during assembly as willbe shown later herein.

To the same end, the lug member 106 includes a lug portion 126 thatengages the work implement 10 and that is unitary with the spacerengaging projection 120. In other embodiments, the lug portion may beseparate from the spacer engaging projection. The lug portion 126 mayinclude a rear facing hook portion 128 that catches the underside of thework implement 10, also helping to prevent the unintentional removal ofthe attachment system 100.

For the particular embodiment shown in FIGS. 2 and 3, the spacer 104includes a cylindrical body 130, and a bottom flat surface 132 (e.g. ahorizontal surface as best seen in FIG. 3). Other configurations for thespacer are possible in other embodiments of the present disclosureincluding rectangular, etc. Also, a top flat surface 134 (e.g. ahorizontal surface) may also be provided that has a threaded hole 136for lifting the spacer 104. This feature may be omitted in otherembodiments of the present disclosure.

As best seen in FIG. 2, the front facing surface 122 a may match thecylindrical body 130 of the spacer 104 (e.g. a convex arcuate surfaceand a concave arcuate surface interface), and as best seen in FIG. 3,the second spacer engaging surface 124 may be flat (e.g. a horizontalsurface), contacting the bottom flat surface 132 of the spacer 104.Thus, this surface 124 provides a platform for the spacer 104 to sit onin some embodiments. This feature may be omitted in other embodiments ofthe present disclosure.

Looking at FIGS. 3, and 13-15, the lug member 106 may include anupwardly extending wall 138 that is disposed between the first end 116,and the second end 118 of the slide platform 108 along the slidingdirection 112, and the sliding boss member 114 includes an upwardlyextending head 140 that is disposed proximate the second end 118 of theslide platform 108 of the lug member 106 along the sliding direction112.

At least one compression bolt assembly 142 may be interposed between theupwardly extending wall 138 of the lug member 106 and the upwardlyextending head 140 of the sliding boss member 114. This assembly 142 maybe used to move the sliding boss member 114 relative to the lug member106 in a manner that will be discussed in detail momentarily herein.

A pin member 144 may also be provided to limit the slide distance of thesliding boss member 114 as it rides in the slide groove 110 of the slideplatform 108 of the lug member 106. More specifically, the sliding bossmember 114 includes a slide portion 146 that extends forward from theupwardly extending head 140. The slide portion 146 may define a verticalthru-hole 148 (see FIG. 3), and the slide platform 108 of the lug member106 may define an elongated slot 150 that is in communication with thevertical thru-hole 148. The pin member 144 is disposed in the verticalthru-hole 140 and the elongated slot 150. So, the pin member contactsthe extremities of the elongated slot 150 (e.g. see FIGS. 3 and 7) asthe slide portion 114 extends and slides through the thru-aperture 152of the upwardly extending wall of the lug member 106.

The pin member 144 may take the form of a threaded fastener 154 thatmates with a nut 156 as shown in FIGS. 3 and 10, or some other form suchas a dowel pin, roll pin, etc.

Turning now to FIGS. 10-12, details of the compression bolt assembly 142including how it is constructed, assembled, and operated to effectuatemovement of the sliding boss member 114 will now be discussed.

Starting with FIG. 10, the compression bolt assembly 142 may comprise abolt 158 with a hex head 160, and a threaded shaft 162. Thumb nut 164and jam nut 166 may be threaded onto the threaded shaft 162. Beforethat, a nut spacer 168 may also be placed onto the threaded shaft 162that is disposed proximate to the hex head 162, but not necessarily so.The head hex 160 may be placed into the recess 170 (that is blind) foundon the upwardly extending wall 138 next to the thru-aperture 152. Therecess 170 may be at least partially complimentarily shaped to receivethe head hex 160 and prevent the bolt 158 from rotating once installedtherein.

After the compression bolt assembly 142 has been attached to the lugmember 106′, the sliding boss member 114 may slide into the slide groove110′ until the free end of the threaded shaft 162 passes into aclearance hole 172 found on the upwardly extending head 140 of thesliding boss member 114 (see FIG. 12). Two such compression boltassemblies may be provided as shown, but not necessarily so. Otherconfigurations of the compression bolt assembly 142 and its componentsare possible in other embodiments of the present disclosure.

As indicated by FIG. 11, initially the thumb nut 164 and jam nut 166 areloose relative to each other and the nut spacer 168, allowing the thumbnut 164 to rotate. Rotating in one direction will cause the thumb nut164 to push on the upwardly extending head 140, causing the sliding bossmember 114 to move inwardly away from the lug member 106′ toward theinterior of the work implement. Rotating in the other direction willcause clearance to be formed between the upwardly extending head 140 andthe thumb nut 164, allowing the user to push on the upwardly extendinghead 140, moving the sliding boss member 114 outwardly toward the lugmember 106′ and the lip of the work implement. Typically, the slidingboss member 114 is pushed toward the lip so that the lock retainer 52 ofthe retaining mechanism 50 may be rotated to lock the wear member 14onto the work implement. Then, the sliding boss member 114 is pulled outvia the 164 thumb nut so that snug contact is made between the boss 102and the lock retainer 52 (see also FIG. 3).

In FIG. 12, once the desired position has been achieved, the jam nut 166is tightened to impinge on the thumb nut 164, helping to maintain thisdesired position so that the work implement is ready for use.

Focusing now on FIGS. 13-15, an attachment assembly 200 that may beprovided as a replacement kit or as a retrofit in the field for theattachment system 100 will now be described.

The attachment assembly 200 may comprise a spacer 104, and a lug member106 including a slide platform 108 defining a slide groove 110 thatfurther defines a sliding direction 112, a first end 116 that isdisposed along the sliding direction 112, and a second end 118 that isdisposed along the sliding direction 112. As alluded to earlier herein,the lug member 106 may also include a spacer engaging projection 120defining a spacer engaging surface 122 disposed proximate to the firstend 116 of the slide platform 108 along the sliding direction 112.

The lug member 106 may also include a work implement engaging lug 126 athat extends downwardly from slide platform 108 and that is disposedproximate to the first end 116 of the slide platform 108 along thesliding direction 112 (i.e. closer to the first end 116 than the secondend 118). The work implement engaging lug 126 a may define a frontsurface 122 b that defines the spacer engaging surface 122.

The spacer 104 may include a cylindrical configuration including aconvex cylindrical surface 202 (may be cylindrical, conical, elliptical,polynomial, etc.), and the spacer engaging surface 122 may include aconcave arcuate surface 204 that is configured to engage the convexcylindrical surface 202, possibly in a matching fashion. Otherconfigurations of these surfaces are possible in other embodiments ofthe present disclosure. The spacer engaging surface may have a“V-shaped” configuration, etc.

The spacer 104 defines a top surface 134 a with a threaded hole 136, anda bottom surface 132 a. The work implement engaging lug 126 a may definea spacer engaging bottom surface 124 a that is configured to engage thebottom surface 132 a of the spacer 104. These features may be omitted inother embodiments of the present disclosure.

As shown in FIGS. 13-15, the slide groove 110 extends completely throughthe slide platform 108 from the first end 116 to the second end 118 ofthe slide platform 108. This may not be the case for other embodimentsof the present disclosure.

With continued reference to FIGS. 13-15, a lug member 106 that may besupplied as a replacement part or a retrofit in the field for use withthe attachment system 100 or attachment assembly 200 as describedearlier herein will now be discussed.

The lug member 106 may include a slide platform 108 that defines a slidegroove 110 that further defines a sliding direction 112, a first end 116that is disposed along the sliding direction 112, and a second end 118that is disposed along the sliding direction 112. The lug member 106 mayalso have a spacer engaging projection 120 extending downwardly from theslide platform 108.

The spacer engaging projection 120 may define a front facing stopsurface 122 c, and a bottom stop surface 124 b that are configured toengage the spacer 104. One or more of these surfaces 122 c, 124 b may bedifferently configured than shown or may be omitted altogether, etc. inother embodiments of the present disclosure.

In some embodiments, the spacer engaging projection 120 is also a wearimplement engaging projection 126 including a rear facing hook portion128 a. Other configurations are possible in other embodiments of thepresent disclosure.

The spacer engaging projection 120 is disposed proximate to the firstend 116 of the slide platform 108, and the lug member 106 furthercomprises a compression bolt assembly engaging portion 138 a thatextends upwardly from the slide platform 108, and that is disposedbetween the wear implement engaging projection 126 b and the second end118 of the slide platform 108 along the sliding direction 112.

The lock retainer, the sliding boss member, and the lug member may bemade from a rigid material such as steel, iron, grey-cast iron, castiron, etc.

It should be noted that the particulars of the retaining mechanism, theattachment system, the attachment assembly, the sliding boss member, andthe lug member as well as their construction, configuration, method ofassembly, etc. are provided by way of an example only and it iscontemplated that other embodiments of the present disclosure arepossible.

The arrangement, function, and dimensions of the various features of anyembodiment of a sliding boss member and lug member as discussed hereinmay be altered as needed or desired to be different than what has beenspecifically mentioned herein.

INDUSTRIAL APPLICABILITY

In practice, a lug member, an attachment assembly, an attachment system,a work implement using any of the aforementioned, or a machine using anyof these components according to any embodiment described herein may besold, bought, manufactured or otherwise obtained in an OEM (originalequipment manufacturer) or after-market context.

The attachment system 100 may be assembled and used as follows forattaching a wear member 14 to a work implement 10.

The method 300 may comprise the following steps. First, the sliding bossmember, the lug member, and the compression bolt assembly are assembledas shown in FIG. 10 (see arrows labeled 302).

Then, this subassembly is inserted into the aperture of the workimplement as shown in FIG. 4 (see arrow 304).

Once fully inserted into the aperture, this subassembly moved to therightmost position until the lug engages the work implement as shown inFIG. 5 (see arrow 306). At about the same time, the sliding boss memberis moved to the right (see arrow 308).

Now, the spacer may be inserted into the aperture (see arrow 310 in FIG.7) until it engages both the lug member and the work implement as shownin FIG. 8.

Next, the sliding boss member is moved to the left (see arrow 312 inFIG. 8), trapping the spacer in place as shown in FIG. 9. Now, theattachment system is locked onto the work implement and may not beunintentionally removed.

The wear member is inserted over the lip of the work implement(represented by arrow 314 in FIG. 3) and the retainer lock is rotated(represented by arrow 316 in FIG. 11), fixing the wear member onto thework implement. Some fine tune adjustment may also be performed beforeand after rotating the retainer lock as previously discussed herein withreference to FIGS. 11 and 12.

If a wear member becomes worn or it becomes desirable to maintain anycomponent of the attachment system, the user may rotate the lockretainer with a tool such as a ratchet into the unlocked configuration.Then, the wear member may be removed. The attachment system may bedisassembled by reversing the steps of method 300. The aforementionedapparatus and method may allow for easier and more reliable assembly anddisassembly for wear members attached to work implements including thosethat are already in the field.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments of theapparatus and methods of assembly as discussed herein without departingfrom the scope or spirit of the invention(s). Other embodiments of thisdisclosure will be apparent to those skilled in the art fromconsideration of the specification and practice of the variousembodiments disclosed herein. For example, some of the equipment may beconstructed and function differently than what has been described hereinand certain steps of any method may be omitted, performed in an orderthat is different than what has been specifically mentioned or in somecases performed simultaneously or in sub-steps. Furthermore, variationsor modifications to certain aspects or features of various embodimentsmay be made to create further embodiments and features and aspects ofvarious embodiments may be added to or substituted for other features oraspects of other embodiments in order to provide still furtherembodiments.

Accordingly, it is intended that the specification and examples beconsidered as exemplary only, with a true scope and spirit of theinvention(s) being indicated by the following claims and theirequivalents.

What is claimed is:
 1. A lug member for use with attachment system for attaching wear members to a work implement using a spacer, the lug member comprising: a slide platform defining a slide groove that further defines a sliding direction, a first end that is disposed along the sliding direction, and a second end that is disposed along the sliding direction; and a spacer engaging projection extending downwardly from the slide platform.
 2. The lug member of claim 1, wherein the spacer engaging projection defines a front facing stop surface and a bottom stop surface that are configured to engage the spacer.
 3. The lug member of claim 1, wherein the spacer engaging projection is also a wear implement engaging projection including a rear facing hook portion.
 4. The lug member of claim 3, wherein the spacer engaging projection is disposed proximate to the first end of the slide platform, and the lug member further comprises a compression bolt assembly engaging portion that extends upwardly from the slide platform, and that is disposed between the wear implement engaging projection and the second end of the slide platform along the sliding direction.
 5. The lug member of claim 1, further comprising a work implement engaging lug connected to the spacer engaging projection that defines a front surface that defines a spacer engaging surface.
 6. The lug member of claim 5, wherein the spacer engaging surface includes a concave arcuate surface.
 7. The lug member of claim 5, wherein the work implement engaging lug defines a shelf surface that is configured to contact a spacer.
 8. The lug member of claim 5, wherein the work implement engaging lug, the spacer engaging projection are unitary, and are attached to the slide platform that is a different component.
 9. The lug member of claim 7, wherein the implement engaging lug further comprises a rearward facing hook that is disposed at a level that is vertically below the shelf surface.
 10. The lug member of claim 1, wherein the slide platform defines an elongated slot that is in communication with the slide groove.
 11. The lug member of claim 1, further comprising a head extending upwardly from the slide platform. 